棉蚜对寄主的选择及寄主专化型研究

采用叶片选择法，生命表及EPG技术研究了棉蚜对寄主植物的选择和专化性，结果表明，棉花上生长的棉蚜对棉花，西葫芦和西瓜叶片均具有强选择性，而对黄瓜和南瓜选择性弱，西瓜，南瓜和黄瓜上生长的棉蚜对其原寄主选择性强，而对棉花选择性弱，棉花上的棉蚜转接到黄瓜和南瓜上，其存活率和繁殖力极低，棉蚜的取食行为在黄瓜和马铃薯，黄瓜和棉花之间存在明显的寄主专化型，黄瓜与棉花上的棉蚜相互转接均难成功，而黄瓜和马铃薯上的棉蚜转移具有不对称性。

Studies on Cotton Aphid Aphis gossypii Selectivity to Host and Its Host-type

The cotton aphid, Aphis gossypii, is a worldwide and polyphagous pest. The host plants are more than 300 species in various botanical families. The adaptations of this aphid to various host plants are different, but so far, the special host|biotypes of cotton aphid have not been identified. In this paper, the selectivity of cotton aphid to different host plants, the survival rate, reproduction capability and feeding behavior of the aphid after host transformation are studied by directional selection, host transformation and feeding record(EPG) methods. ;The results showed that the aphids originally feeding on cotton preferred cotton, summer squash, and water melon leaves to cucumber and pumpkin leaves. While the aphids on the water melon, pumpkin and cucumber had a preference for their original host plants to cotton leaves. The selecting rates of cotton aphid originally feeding on water melon, pumpkin and cucumber leaves to cotton leaves were 34^3%, 38^5% and 29^8%, respectively, but they were 53^8%, 52^1% and 56^9%, respectively on their original host plants. ; The survival rates and net reproductions of the cotton aphid after transformation were also studied by life|table method. It was found that after transforming from cotton to cucumber and pumpkin, the survival rates and net reproductions of aphids were only 3^54%, 1^813 and 12^43%, 0^162, respectively. They were 40% and 0^902, while the aphids transformed from cucumber to cotton. ;After host transformation the continual feeding behavior of the cotton aphid in 4 hours was recorded and analyzed by electrical penetration graphs (EPG) technique. The results showed that the proportion of wave form E was very low after inter|transformation between cotton and cucumber leaves, and the value is 5^79% and 0^05%, respectively. And the total proportion of non|feeding and probing waves (np+C) was as high as to 68^45% and 68^47%. But in those transformations, such as from potato or pumpkin to cotton, pumpkin to cucumber and cucumber to potato, the proportions of wave E were more than 20%, and the waves of np+C were less than 60%. The proportion of wave E was low for the aphids feeding on potato leaves transformed to cucumber, but on the contrary, it was high. The asymmetric feeding behavior of the cotton aphid was existed on potato and cucumber leaves.; In conclusion the cotton aphid feeding on different host plants has different capabilities of selecting and adapting to cotton, cucurits and potato leaves. Moreover, the cotton aphid has exhibited significent host biotypes on cucumber and cotton. The transformation roads of the cotton aphid among various host plants may be symmertical or asymmetrical.